Positive feeding structure for tools incorporating pressure controlled feed member

ABSTRACT

A feed member telescopes and is threadably engaged with a rotatably driven spindle arranged for moving the spindle axially in a feed stroke upon the feed member rotating faster than the spindle and in a retraction stroke upon the feed member remaining stationary. The feed member is also arranged axially movable along the spindle a limited distance between first and second positions controlled for remaining stationary in the first position and rotating faster then the spindle to, at and from the second position. A fluid actuated piston reacts against the feed member controlled to urge the feed member axially toward and normally retain the same in the second position at the commencement and during the spindle feed stroke, the feed member causing the spindle feed stroke upon reaching the second positon and causing the retraction stroke upon the return to the first position so that when the spindle in the feed stroke meets resistance against spindle axial movement overcoming the action of the fluid piston, the feed member returns from second to first position for start of the retraction stroke.

United States Patent [191 Quackenbush POSITIVE FEEDING STRUCTURE FORTOOLS INCORPORATING PRESSURE CONTROLLED FEED MEMBER- [75] Inventor:Robert C. Quackenbush, Glendale,

Calif.

[73] Assignee: Arthur B. Quackenbush, Glendale, Calif. a part interest22 Filed: Nov. 24, 1972 21 Appl. No.: 309,147

Germany 173/145 Primary Examiner'--Ernest R.- Purser Attorney, Agenl. 0rFirm-Mahoney, Schick &-Cislo Mar. 19, i974 [57] ABSTRACT A feed membertelescopes and is threadably engaged with a rotatably driven spindlearranged for moving the spindle axially in a feed stroke upon the feedmember rotating faster than the spindle and in a retraction stroke uponthe feed member remaining stationary. The feed member is also arrangedaxially movable along the spindle a limited distance between first andsecond positions controlled for remaining stationary in the firstposition and rotating faster then the spindle to, at and from the secondposition. A fluid actuated piston reacts against the feed membercontrolled to urge the feed member axially toward and normally retainthe same in the second position at the commencement andduring thespindle feed stroke, the feed member causing the spindle feed strokeupon reaching the second positon and causing the retraction stroke uponthe return to the first position so that when the spindle in the feedstroke meets resistance against spindle axial movement overcoming theaction of the fluid piston, the feed member returns from sec- 0nd tofirst position for start of the retraction stroke.

I2 Claims, 7 Drawing Figures QHIIIIIQI;

minnows mm 13797583 SHEET 3 UF 3 Fig. 7.

POSITIVE FEEDING STRUCTURE FOR TOOLS INCORPORATING PRESSURE CONTROLLEDFEED MEMBER BACKGROUND OF THE INVENTION This invention relates to apositive feeding structure for tools which incorporates a pressurecontrolled feed member and more particularly, to such a structure havinga feed member threadably engaged with the peripheral threads of spindleand axially movable a limited distance as determined by applied fluidpressure for accomplishing the feed and retraction control of thespindle. Furthermore, in the preferred form of the present invention,the combination of the fluid pressure reacting against the feedmemberand the fluid flow may be effectively used for controlling the rotationof the feed member to thereby control the action of the feed memberonthe spindle and the spindle axial movement in the feed and retractionstrokes. These and other features of the positive feeding structure ofthe'present invention will be discussed and described in the followingspecification and claims.

In my prior US. Pat. No. 3,411,593 entitled Tool Incorporating PositiveFeeding Structure, there is described and claimed a tool having arotatably driven spindle controlled in feed and retraction strokes by afeed member threadably engaged with peripheral threads formed on thespindle. The feed member is retained axially stationary and is rotatedfaster than the spindle rotation to produce axial threaded movement ofthe spindle relative thereto producing the spindle feed stroke. Atcompletion of the feed stroke, rotation of the feed member isdiscontinued and the feed member retained rotatably stationary with thecontinued rotation of the spindle reversely axially threadably movingthe spindle relative to the feed member to accomplish the retractionstroke.

Unless selectively manually carried out by an operator, the shifting ofthe tool from the feed to the retraction strokes is carried out by apivotal lever engaged by a preset control collar on the spindle. As thespindle reaches the end of the feed stroke, the control collar engagesthe pivotal lever shifting the same to a position actuating certainfluid valves whichaffects the drive to the feed member to stop the feedmember and retain it stationary thereby commencing the. spindleretraction stroke. Thus, unless earlier terminated by manual operatoraction, the tool, once the spindle feed stroke is started, will alwayscarry out a complete predetermined feed stroke before commencing thespindle retraction stroke.

Proper control of the tool, therefore, obviously requires strictoperator attention. It is true that no problems will be presentedprovided the spindle can always move completely through its feed strokeand then return in its retraction stroke, but if the particular cuttingor forming device mounted on and driven by the spindle meets anunpredicted obstruction intermediate the spindle feed stroke, only quickoperator action in manual control can immediately terminate the spindlefeed stroke and begin spindle movement in its retraction stroke. If theoperator does not so act, damage to a workpiece being worked upon, thecutting or forming device on the spindle, or even the spindle and otherportions of the tool may be severely damaged.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of thisinvention to provide a positive feeding. structure forv tools whichincorporates a pressure controlled feed member wherein the feed member,despite feed member threaded engagement with the spindle periphery, isaxially movable between a first position in which it is controlled tocarry out the spindle retraction stroke and a second position in whichit is controlled to carry out the spindle feed stroke with the feedmember being retained in its second position by fluid pressure. Thus,upon the spindle in its axially moving feed stroke meeting an axialrestraning pressure greater than the fluid pressure maintaining the feedmember in its second position, the greater restraining pressure willcause the feed member to move from its second back to its first positionfor being controlled to commence the restraction stroke. The restrainingpressure on the spindle overcoming the fluid pressure and ultimatelycausing commencement of the retraction stroke may be that created by asufficient obstruction opposing spindle feed stroke movement or may be apreset stop member located to always determine the predetermined extentof the spindle feed stroke.

It is a further object of this invention to provide a positive feedingstructure for tools which incorporates a pressure controlled feed memberand including the foregoing elements and operating in the foregoinggeneral manner wherein the flow of fluid, preferably liquid such ashydraulic fluid or oil, which provides the fluid pressure controllingthe feed member movement may be used to automatically control the feedmember and spindle actuations, thereby automatically switching thespindle from feed stroke movement to retraction stroke movement upon therestraining pressure overcoming the fluid pressure as the result of thespindle either meeting an obstruction or completing its predeterminedfeed stroke. In the preferred form, the fluid pressure is directedagainst the feed member at the desired commencement of the spindle feedstroke and while the feed member is in the first position, and the samecontrol member controlling such fluid pressure direction controls thefeed member rotation to start the feeding member rotation faster thanthe spindle rotation. This causes the rotating spindle to remain axiallystationary while the fluid pressure forces the feed member to movethreadably along thespindle to the feed member second position followedby commencement of the spindle axial movement in the feed stroke whenthe feed member reaches its second position. When the spindle reachesthe end of its feed stroke as caused by either an obstruction or apreset stop member preventing further spindle feed stroke movement, therestraining forces on the spindle exceed the fluid pressure retainingthe feed member in its second position so that the feed member must movethreadably along the spindle back to its first position forcing reverseflow of the fluid creating the fluid pressure and with such reversefluid flow reactivating the actuating means to stop the feed member tostart the spindle retraction stroke.

These and other objects of the invention will become apparent as thedescription proceeds herein when taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. I is a side elevational view of an embodiment of tool incorporatingthe principles of the present invention, the tool being shown with thespindle thereof in retracted position ready for the initiation of aspindle feed stroke;

FIG. 2 is a top plan view looking in the direction of the arrows 22 inFIG. 1;

FIG. 3 is an enlarged, fragmentary, vertical sectional view looking inthe direction of the arrows 3-3 in FIG.

FIG. 4 is an enlarged, fragmentary, vertical sectional view looking inthe direction of the arrows 4-4 in FIG. 2, but with the tool controlsshifted and the various tool elements shifted commencing the spindlefeed stroke;

FIG. 5 is a fragmentary, horizontal sectional view looking in thedirection of the arrows 5-5 in FIG. 4;

FIG. 6 is a view similar to FIG. 4, but with the tool controls shiftedand the various tool elements shifted commencing the spindle retractionstroke; and

FIG. 7 is a fragmentary horizontal sectional view looking in thedirection of the arrows 7-7 in FIG. 6.

DESCRIPTION OF THE BEST EMBODIMENT CONTEMPLATED:

Referring to the drawings, the positive feeding structure incorporatingthe pressure controlled feed member of the present invention is shownforming a part of a right angle drive tool of the general type forrotatably driving working members such as drills through feed andretraction strokes in the carrying out of a drilling operation.Furthermore, the principles of the present invention constitute animprovement of the structure described and claimed in my prior US. Pat.No. 3,4l 1,593 entitled Tool Incorporating Feeding Structure with thetool described herein having many common elements and mechanisms to thetool described in said prior patent.

As shown, the tool includes a housing generally indicated at 10 mountingmain drive means preferably in the form of an air driven drive motor 12of generally usual form connected through a somewhat usual gear traingenerally indicated at 14 to a secondary spindle drive gear 16. Thesecondary spindle drive gear 16 is in turn, drivingly connected to aprimary spindle drive gear 18 telescoping and spline connected to aperipherally threaded spindle 20. The spindle 20 is mounted in thehousing 10 axially movable in feed and retraction strokes rotatablycarrying a working end 22 to and from a workpiece in somewhat usualmanner and with the primary spindle drive gear 18 spline connectedthereto, rotatable drive of the spindle is maintained at all times whilethe primary and secondary spindle drive gears 16 and 18 remain axiallystationary.

A spindle feed member or feed gear 24 is also telescoped over thespindle 20 spaced above the primary spindle drive gear 18 but isthreadably engaged with the peripherally threaded spindle and is alsoaxially movable withinthe housing a limited axial distance between anupper first position shown in FIG. 6 and a lower second position shownin FIG. 4. Rotation of the feed member or gear 24 is controlled by afeed member drive gear 26 spline connected thereto and likewise mountedwithin the housing 10 for limited axial movement as well as rotation incertain axial positions. Thus, the feed gear 24 and the feed memberdrive gear 26 remain at all times rotatably connected while beingaxially movable independent of each other their respective limited axialdistances.

As can be seen in FIGS. 4 and 6, the feed member drive gear 26 has alower axle portion 28 projecting downwardly into a sleeve bearing 30 andan upper axle portion 32 projecting upwardly into a needle bearing 34.The lower axle portion 28 is positioned for engagement by a piston 36 ofa retraction stroke air cylinder 38 and the upper axle portion 32 ispositioned for engagement by a piston 40 of a feed stroke air cylinder42 through a ball 44. Also, a series of control pins 46 project throughand from the feed member drive gear 26 for engagement in appropriateopenings 48 of the secondary spindle drive gear 16 when the feed memberdrive gear is in its lower position as shown in FIG. 4 and forengagement in appropriate openings 50 in the housing 10 formed partiallyby a gear stop 52 when the feed member drive gear is in its upperposition as shown in FIG. 6. Therefore, when the feed member drive gear26 is in its lower position engaged with the secondary spindle drivegear 16, it is rotatable with the secondary spindle drive gear and inturn, rotates the feed member 24, but when the feed member drive gear 26is in its upper position engaged with the housing 10, the feed memberdrive gear is retained stationary retaining the feed member stationary.It is important to note, however, that the ratios between the secondaryand primary spindle drive gears 16 and 18 and between the feed memberdrive gear and feed member 26 and 24 are different such that therotatable speed of the spindle 20 is less than the rotatable speed ofthe feed member 24 when the feed member is rotated. Obviously, therotational speed of the feed member 24 is reduced below the speed of thespindle 20 when the feed member'drive gear 26 is engaged with thehousing. 10 since the feed member is then stationary while the spindlecontinues it constant rotation.

A fluid cylinder 54, preferably actuated by a liquid such as hydraulicfluid or oil, is formed in the housing directly above the feed member 24and likewise telescoping the spindle 20, although spaced slightlyoutwardly therefrom in the housing. The fluid cylinder 54 includes anannular lower abutment member 56 downwardly actionable against the feedmember 24, an annular piston 58 downwardly engaging the abutment memberand an annular seal 60 downwardly abutting the piston. Upwardly of theseal 60, as best seen in FIGS. 5 and 7, the fluid cylinder 54 isconnected through a passage 62 to a two-part fluid chamber 64, one partof which is closed by a threadably adjustable filler plug 66 and theother part of which is movably closed by an axially extending plunger 68forming a part of a piston 70 of a feed actuating cylinder 72.

Within feed actuating'cylinder 72 and axially opposite the plunger 68, acontrol rod 74 projects axially from the piston 70 through a guide block76 forming the opposite end closure of the feed actuating cylinder. Ascan be seen in FIG. 7, when the piston 70 is positioned fully at thecontrol rod end of the feed actuating cylinder 72, the control rod 74projects through the guide block 76 and a determined distance therefromengageable with an end 78 of a pivotal hand control lever 80. Anopposite end 82 of the hand control lever is similarly engageable with acontrol rod 84 of a shuttle valve 86, the control rod 84 and shuttlevalve 86. normally being axially urged toward the hand control lever 80by a spring 88.

The shuttle valve 86 is connected to an air supply and when in the righthand position as shown in FIG. 5 supplies air to the right hand orcontrol rod side of the piston 70 within the feed actuating cylinder 72,as well as through a line 90 to the feed stroke air cylinder 42 againstthe piston 40 thereof. When the shuttle valve 86 is in the left handposition as shown in FIG. 7, air to the feed actuating cylinder 72 andfeed stroke air cylinder 42 is cut off while air is directed in a line92 to the retraction stroke air cylinder 38 against the piston 36thereof. For purposes to be hereinafter more clearly explained during adescription of the operation of the tool, it will be noted that thepreferred liquid in the fluid cylinder 54 and fluid chamber 64 isisolated from the air in the feed actuating cylinder 72, appropriateseals being employed as shown for this purpose. Also, as shown in FIG.3, the hand control lever 80 is releasably retained in its maximumclockwise pivoted position as shown in FIG. 7 by a detent 94 of usualform engageable therewith.

Finally, a feed stroke limiting collar 96 is telescoped over the upperend of the spindle 20 adjustably secured to the spindle at the desiredlocation for limiting the extension of the spindle from the housing 10in its feed stroke and determining the location of the start of theretraction stroke. When the spindle has extended a maximum in its feedstroke as preset by the collar 96, the collar downwardly engages againstan abutment member 98 on the housing 10 as shown in FIGS. 4 and 6. This,of course, creates a restraining force .on the spindle 20 preventingfurther feed stroke axial movement as will be hereinafter described indetail.

In operation of the embodiment of the tool shown and described herein,and starting with the spindle 20 fully retracted and the variouselements in retraction stroke positioning as they would be attermination of the retraction strokes, such elements are initially inthe positions shown in FIGS. 6 and 7. In such positions, the

feed member 24 is in its upper position and the feed member drive gear26 is in its upper position locked stationary with the gear stop 52 andhousing 10. Also, the piston 70 of the feed actuating cylinder 72 is inits right hand position, the hand control lever 80 is pivoted fullyclockwise retaining the shuttle valve 86 in its left hand position, andthe main drive motor 12 is not actuated.

To start the spindle feed stroke, air is directed to the main drivemotor 12 beginning constant rotation of the spindle 20 through the geartrain 14, secondary spindle drive gear 16 and primary spindle drive gear18. Also, the hand control lever 80 is pivoted counterclockwise forcingrelease of the detent 94 and with such hand control lever movementforcing the control rod 74 to the left, in turn, forcing the piston 70and plunger 68, all of the feed actuating cylinder 72 to the left. Stillfurther, this counterclockwise pivoting of the hand control lever 80releases the control rod 84 of the shuttle valve 86 permitting thespring 88 to move the shuttle valve to its right hand position directingair to the feed actuating cylinder 72 and the feed stroke air cylinder42 while cutting off air to the retraction stroke air cylinder 38, asshown in FIG. 5.

Referring to both FIGS. 4 and 5, air to the feed stroke air cylinder 42causes the piston 40 thereof to move the feed member drive gear 26downwardly from its stationary locked engagement with the housing 10 toengagement with and rotation by the secondary spindle drive gear I6causing rotation of the feed member 24 faster than the spindle 20 and inthe same direction. Pressurized air into the feed actuating cylinder 72creates a pressure against the piston tending to move the same to theleft creating an air pressure to the left against the plunger 68 andsuch pressure reacts against the liquid'within the fluid chamber 64 andfluid cylinder 54 so as to ultimately react against the piston 58 urgingthe feed member 24 downwardly from the position shown in FIG. 6 to theposition shown in FIG. 4. With the feed member 24 rotating faster thanthe spindle 20 and the downward force against the feed member by thefluid cylinder 54, the spindle initially remains axially stationary andthe feed member threads downwardly along the spindle from the positionshown in FIG. 6 to the position shown in FIG. 4 and upon reaching thislower position, the feed member becomes axially stationary and thespindle begins to feed downwardly in its feed stroke.

Thus, the various elements retain the positioning shown in FIGS. 4 and 5with the fluid cylinder 54 continuing to exert a downward pressureagainst the feed member 24 throughout the feed stroke of the spindle 20.It will be noted that such pressure by the fluid cylinder 54 ismaintained as a result of the piston 70 of the feed actuating cylinder72 having progressively moved to the left as the feed member 24 moveddownwardly and as caused by the air through the shuttle valve 86 andinto the feed actuating cylinder. Therefore, as long as the feed member24 can be retained in this lower position as shown in FIG. 4 by thefluid cylinder 54, the feed stroke of the spindle 20 will be continued,so that the extent of the spindle feed stroke will be determined by whenthe spindle meets an axially restraining force sufficient to overcomethe downward force of the fluid cylinder 54 against the feed member 24as created by an obstruction of some form prior to engagement of thefeed stroke limiting collar 96 with the housing 10 or the engagement ofthis collar with the housing, in either case the reaction being thesame.

In either case, when a sufficient axial restraining force is exertedagainst and in opposition to the feed stroke of the spindle 20, thespindle can no longer move axially in its feed stroke direction ordownwardly as shown in FIG. 4 so that the feed member 24 begins tothread upwardly along the spindle and against the pressure of the fluidcylinder 54. This upward threading of the feed member 24 along thespindle 20 from the position shown in FIG. 4 back to the position shownin FIG. 6 causes the liquid within the fluid cylinder and the fluidchamber 64 to react against the piston 70 in the feed actuating cylinder72 through the plunger 68. This compresses the air within the feedactuating cylinder 72 by movement of the piston 70 thereof to the rightfrom the position shown in FIG. 5 to the position shown in FIG. 7,causing the control rod 74 to project through the guide block 76 andengage the end 78 of the hand control lever 80 shifting this handcontrol lever clockwise back to the position shown in FIG. 7.

The repositioning of the hand control lever 80 clockwise causes thelever end 82 to force the control rod 84 of the shuttle valve 86 to theleft repositioning the shuttle valve to the left as shown in FIG. 7.This cuts off 'air to the feed actuating cylinder 72 and the feed strokeair cylinder 42 while directing air to the retraction stroke aircylinder 38 against the piston 36 thereof. The retracting stroke aircylinder 38, therefore, forces the feed member drive gear 26 upwardlyfrom engagement with the secondary spindle drive gear 16 and ultimatelyupwardly into stationary engagement with the gear stop 52 and thehousing 10 ceasing rotation of the feed member 24 and retaining the samestationary.

Thus, when the spindle 20 in the feed stroke meets the axial restrainingpressure either from the feed stroke limiting collar 96 or otherwise,the spindle dwells in axial movement, that is, remains in a dwellposition axially stationary, until the feed member 24 has threadedaxially upwardly from its lower position shown in FIG. 4 to its upperposition shown in FIG. 6, and then through the reduction of therotational speed of the feed member drive gear 26 and feed member belowthe rotational speed of the spindle, in this case rotationallystationary, the spindle 20 begins upward movement in its retractionstroke. Furthermore, the spindle 20 continues in its retraction strokeupward movement and the various elements'are retained in the positionsshown in FIG. 6 for the determined retraction stroke. Upon completionthereof, air to the drive motor 12 is cut off and the cycle is completewith a new cycle being started in the exact same manner as hereinabovedescribed.

As was hereinbefore pointed out, in the operation of the tool for acomplete cycle of spindle feed and retraction strokes, at the beginningof the feed stroke, it is necessary for the feed member 24 to threaddownwardly along the constantly rotating spindle 20 from the feed memberupper position shown in FIG. 6 to the feed member lower position shownin 'FIG. 4 which feed member threading and repositioning takes placewhile the spindle is axially stationary. Also, at the end of the feedstroke and prior to commencement of the retraction stroke, the spindle20 is being restrained axially stationary while the feed member 24threads upwardly therealong from the position shown in FIG. 4 to theposition shown in FIG. 6. Thus, during these two periods of time whenthe feed member 24 is moving axially, the spindle 20 is in dwellpositions as far as axial movement thereof is concerned and these dwellpositions in period of time are determined by the amount of movement ofthe piston 70 within the feed actuating cylinder 72 required to move thefeed member 24 as well as control the shuttle valve 86.

Since the fluid within the fluid cylinder 54 is a liquid and virtuallyincompressible for a closed and properly sealed system, the volumethereof remains constant and the movement of the piston 70 of the feedactuating cylinder 72 is, in effect, determined by the overall volume ofthe fluid cylinder 54 and the fluid chamber 64, again assuming aconstant volume of liquid. Thus, with the filler plug 66 selectivelyadjustable inwardly and outwardly as shown in FIGS. 5 and 7, byadjusting the filler plug inwardly to reduce the overall volume of thefluid cylinder 54 and fluid chamber 64, the feed member 24 from itslower position shown in FIG. 4 is permitted to move upwardly to itsupper position a lesser amount, in other words, the distance betweenthese two positions is less and the dwell periods are, therefore,necessarily less, and an outward adjustment of the filler plug 66 willcreate the opposite reaction lengthening the spindle dwell periods.This, therefore, provides limited spindle dwell period adjustment.

With the tool structure hereinbefore described and shown in theaccompanying drawings, a positive feeding structure for tools isprovided wherein the spindle 20 is automatically shifted from feedstroke movement to retraction stroke movement upon the spindle meeting arestraining force against feed stroke axial movement sufficient toovercome a predetermined force of the fluid cylinder 54. Thus, the toolis automatically shifted from the feed to the retraction stroke when thefeed stroke limiting collar 96 engages the housing 10 according to apredetermined setting of the collar, but equally important, if thespindle engages an unexpected obstruction, the spindle feed stroke willbe terminated and the retraction stroke commenced automatically withoutdamage to the elements of the tool or the workpiece upon which workingoperations are being performed. Furthermore, this automatic regulationof the tool operation may be accomplished directly through the necessaryflow ofliquid within the fluid cylinder 54 and the fluid chamber 64providing such advantageous control in a structure of maximumsimplicity,-yet positive operation.

I claim:

. 1. In a tool incorporating a positive feeding structure of the typehaving a housing mounting a peripherially threaded spindle rotatable andaxially movable in feed and retraction strokes, spindle drive means forrotating said spindle while permitting said axial movement in said feedand retraction strokes, a rotatable feed member threadably engaged withsaid spindle peripheral threads, feed control means shiftable forrotating said feed member at a faster speed than said spindle to axiallymove said spindle in said feed stroke when said feed member is axiallystationary and for reducing said feed member speed below said spindle toaxially move said spindle in said retraction stroke when said feedmember is axially stationary; the improvements comprising: meansmounting said feed member on said housing movable axially between afirst and second position; fluid means operably connected with said feedmember actionable for exerting a predetermined pressure axially againstsaid feed member urging said feed member toward said second position;feed actuating means operably associated with said feed control meansand said fluid means, said feed actuating means shifting said feedcontrol means to rotate said feed member at said faster speed andactuating said fluid means to exert said predetermined pressure whensaid feed member is in said first position initially causing axialthreaded movement of said feed member along said spindle from said firstto said second position and then axial spindle movement in said feedstroke, said feed actuating means shifting said feed control means torotate said feed member at said reduced speed and ceasing actuation ofsaid fluid means upon return of said feed member back to said firstposition from said second position caused by said spindle in said feedstroke receiving an axial restraining pressure greater than and opposingsaid fluid means predetermined pressure followed initially by threadedmovement of said feed member along said spindle from said second to saidfirst position and then axial spindle movement in said retractionstroke.

2. A tool incorporating a positive feeding structure as defined in claim1 in which said feed member is telescoped over said spindle axiallymovable along said spindle between said first and second positions; andin which said fluid means includes an annular piston telescoped oversaid spindle positioned reacting axially against said feed member.

3. A tool incorporating a positive feeding structure as defined in claim1 in which said fluid means includes piston means on said housing spacedfrom said spindle for maintaining fluid pressure against said feedmember during movement of said feed member between said first and secondpositions and in said second position; and in which said feed actuatingmeans includes valve means for controlling said piston means of saidfluid means.

4. A tool incorporating a positive feeding structure as defined in claim1 in which said fluid means includes piston means on said housing spacedfrom said spindle for maintaining fluid pressure against said feedmember during movement of said feed member between said first and secondpositions and in said second position; and in which said feed actuatingmeans includes valve means for controlling said piston means of saidfluid means, hand control means operably associated with said valvemeans for controlling positioning of said valve means.

5. A tool incorporating a positive feeding structure as defined in claim1 in which a selectively adjustable restraining means is operativelyassociated with said spindle for restraining movement of said spindle ata determined end of said feed stroke to provide said axially restrainingpressure greater than the opposing said fluid means predeterminedpressure.

6. A tool incorporating a positive feeding structure as defined in claim1 in which said feed member is telescoped over said spindle movableaxially along said spindle between. said first and second positions; inwhich said fluid means includes an annular primary piston meanstelescoped over said spindle and operatively associated with said feedmember for exerting said predetermined pressure axially against saidfeed member, secondary piston means spaced from said primary pistonmeans for directing fluid under pressure to said primary piston means;and in which said feed actuating means includes valve means operablyassociated with said secondary piston means of said fluid means forcontrolling movement of said secondary piston means.

7. A tool incorporating a positive feeding structure as defined in claim1 in which said feed member is telescoped over said spindle movableaxially along said spindle between said first and second positions; inwhich said'fluid means includes an annular primary piston meanstelescoped over said spindle and operably associated with said feedmember for exerting said predetermined pressure axially against saidfeed member, secondary piston means operably connected to said primarypiston means for supplying liquid under pressure to said primary pistonmeans; and in which said feed actuating means includes valve meansoperably associated with said secondary piston means of said fluid meansand said feed control means, said valve means controlling air againstsaid secondary piston means of said fluid means and controlling air tosaid feed control means for shifting said feed control means.

8. A tool incorporating a positive feeding structure as defined in claim1 in which said feed member is telescoped over said spindle axiallymovable along said spindle between said first and second positions; inwhich said fluid means includes an annular primary piston meanstelescoped over said spindle and operably associated with said feedmember for exerting said predetermined pressure axially against saidfeed member, secondary'piston means spaced from said primary pistonmeans for directing fluid under pressure to said primary piston means;and in which said feed actuating means includes valve means operablyassociated with said secondary piston means of said fluid means forcontrolling movement of said secondary piston means, and control meansoperably associated with said valve means for controlling positioning ofsaid valve means.

9. A tool incorporating a positive feeding structure as defined in claim1 in which said feed member is telescoped over said spindle movableaxially along said spindle between said first and second positions; inwhich said fluid means includes an annular primary piston meanstelescoped over said spindle and operably associated with said feedmember for exerting said predetermined pressure axially against saidleed member, secondary piston means operably connected to said primarypiston means for supplying liquid under pressure to said primary pistonmeans; and in which said feed actuating means includes valve meansoperably associated with said secondary piston means of said fluid meansand said feed control means, said valve means controlling air againstsaid secondary piston means of said fluid means and controlling air tosaid feed control means for shifting said feed control means, andcontrol means operably associated with said valve means for controllingpositioning of said valve means.

10. A tool incorporating a positive feeding structure as defined inclaim 1 in which said feed member is telescoped over said spindlemovable axially along said spindle between said first and secondpositions; in which said fluid means includes an annular primary pistonmeans telescoped over said spindle and operably associated with saidfeed member for exerting said predetermined pressure axially againstsaid feed member, secondary piston means operably connected to saidprimary piston means for supplying liquid under pressure to said primarypiston means; in which said feed actuating means includes valve meansoperably associated with said secondary piston means of said fluid meansand said feed control means, said valve means controlling air againstsaid secondary piston means of said fluid means and controlling air tosaid feed control means for shifting said feed control means, andcontrol means operably associated with said valve means for controllingpositioning of said valve means; and in which a selectively adjustablerestraining means is operably associated with said spindle forrestraining movement of said spindle at a determined end of said feedstroke to provide said axially restraining pressure greater than andopposing said fluid means predetermined pressure.

M. A tool incorporating a positive feeding structure as defined in claim1 in which adjustment means is operably associated with certain of saidfeed member, said fluid means and said feed actuating means forselectively varying distance axially of said spindle between said feedmember first and second positions.

12. A tool incorporating a positive feeding structure as defined inclaim 1 in which said feed member is telescoped over said spindlemovable axially along said spindle between said first and secondpositions; in which said fluid means includes an annular primary pistonmeans telescoped over said spindle and operably associated with saidfeed member for exerting said predetermined pressure axially againstsaid feed member, secondary piston means operably connected to saidprimary piston means for supplying liquid under pressure to said primarypiston means; in which said feed actuating means includes valve meansoperably associated with said secondary piston means of said valve meansand said feed control means, said valve means controlling air againstsaid secondary piston means of said fluid means and controlling air tosaid feed control second positions.

1. In a tool incorporating a positive feeding structure of the typehaving a housing mounting a peripherially threaded spindle rotatable andaxially movable in feed and retraction strokes, spindle drive means forrotating said spindle while permitting said axial movement in said feedand retraction strokes, a rotatable feed member threadably engaged withsaid spindle peripheral threads, feed control means shiftable forrotating said feed member at a faster speed than said spindle to axiallymove said spindle in said feed stroke when said feed member is axiallystationary and for reducing said feed member speed below said spindle toaxially move said spindle in said retraction stroke when said feedmember is axially stationary; the improvements comprising: meansmounting said feed member on said housing movable axially between afirst and second position; fluid means operably connected with said feedmember actionable for exerting a predetermined pressure axially againstsaid feed member urging said feed member toward said second position;feed actuating means operably associated with said feed control meansand said fluid means, said feed actuating means shifting said feedcontrol means to rotate said feed member at said faster speed anDactuating said fluid means to exert said predetermined pressure whensaid feed member is in said first position initially causing axialthreaded movement of said feed member along said spindle from said firstto said second position and then axial spindle movement in said feedstroke, said feed actuating means shifting said feed control means torotate said feed member at said reduced speed and ceasing actuation ofsaid fluid means upon return of said feed member back to said firstposition from said second position caused by said spindle in said feedstroke receiving an axial restraining pressure greater than and opposingsaid fluid means predetermined pressure followed initially by threadedmovement of said feed member along said spindle from said second to saidfirst position and then axial spindle movement in said retractionstroke.
 2. A tool incorporating a positive feeding structure as definedin claim 1 in which said feed member is telescoped over said spindleaxially movable along said spindle between said first and secondpositions; and in which said fluid means includes an annular pistontelescoped over said spindle positioned reacting axially against saidfeed member.
 3. A tool incorporating a positive feeding structure asdefined in claim 1 in which said fluid means includes piston means onsaid housing spaced from said spindle for maintaining fluid pressureagainst said feed member during movement of said feed member betweensaid first and second positions and in said second position; and inwhich said feed actuating means includes valve means for controllingsaid piston means of said fluid means.
 4. A tool incorporating apositive feeding structure as defined in claim 1 in which said fluidmeans includes piston means on said housing spaced from said spindle formaintaining fluid pressure against said feed member during movement ofsaid feed member between said first and second positions and in saidsecond position; and in which said feed actuating means includes valvemeans for controlling said piston means of said fluid means, handcontrol means operably associated with said valve means for controllingpositioning of said valve means.
 5. A tool incorporating a positivefeeding structure as defined in claim 1 in which a selectivelyadjustable restraining means is operatively associated with said spindlefor restraining movement of said spindle at a determined end of saidfeed stroke to provide said axially restraining pressure greater thanthe opposing said fluid means predetermined pressure.
 6. A toolincorporating a positive feeding structure as defined in claim 1 inwhich said feed member is telescoped over said spindle movable axiallyalong said spindle between said first and second positions; in whichsaid fluid means includes an annular primary piston means telescopedover said spindle and operatively associated with said feed member forexerting said predetermined pressure axially against said feed member,secondary piston means spaced from said primary piston means fordirecting fluid under pressure to said primary piston means; and inwhich said feed actuating means includes valve means operably associatedwith said secondary piston means of said fluid means for controllingmovement of said secondary piston means.
 7. A tool incorporating apositive feeding structure as defined in claim 1 in which said feedmember is telescoped over said spindle movable axially along saidspindle between said first and second positions; in which said fluidmeans includes an annular primary piston means telescoped over saidspindle and operably associated with said feed member for exerting saidpredetermined pressure axially against said feed member, secondarypiston means operably connected to said primary piston means forsupplying liquid under pressure to said primary piston means; and inwhich said feed actuating means includes valve means operably associatedwith said secondary piston means of said fluid means and said feedcontrol means, said vaLve means controlling air against said secondarypiston means of said fluid means and controlling air to said feedcontrol means for shifting said feed control means.
 8. A toolincorporating a positive feeding structure as defined in claim 1 inwhich said feed member is telescoped over said spindle axially movablealong said spindle between said first and second positions; in whichsaid fluid means includes an annular primary piston means telescopedover said spindle and operably associated with said feed member forexerting said predetermined pressure axially against said feed member,secondary piston means spaced from said primary piston means fordirecting fluid under pressure to said primary piston means; and inwhich said feed actuating means includes valve means operably associatedwith said secondary piston means of said fluid means for controllingmovement of said secondary piston means, and control means operablyassociated with said valve means for controlling positioning of saidvalve means.
 9. A tool incorporating a positive feeding structure asdefined in claim 1 in which said feed member is telescoped over saidspindle movable axially along said spindle between said first and secondpositions; in which said fluid means includes an annular primary pistonmeans telescoped over said spindle and operably associated with saidfeed member for exerting said predetermined pressure axially againstsaid feed member, secondary piston means operably connected to saidprimary piston means for supplying liquid under pressure to said primarypiston means; and in which said feed actuating means includes valvemeans operably associated with said secondary piston means of said fluidmeans and said feed control means, said valve means controlling airagainst said secondary piston means of said fluid means and controllingair to said feed control means for shifting said feed control means, andcontrol means operably associated with said valve means for controllingpositioning of said valve means.
 10. A tool incorporating a positivefeeding structure as defined in claim 1 in which said feed member istelescoped over said spindle movable axially along said spindle betweensaid first and second positions; in which said fluid means includes anannular primary piston means telescoped over said spindle and operablyassociated with said feed member for exerting said predeterminedpressure axially against said feed member, secondary piston meansoperably connected to said primary piston means for supplying liquidunder pressure to said primary piston means; in which said feedactuating means includes valve means operably associated with saidsecondary piston means of said fluid means and said feed control means,said valve means controlling air against said secondary piston means ofsaid fluid means and controlling air to said feed control means forshifting said feed control means, and control means operably associatedwith said valve means for controlling positioning of said valve means;and in which a selectively adjustable restraining means is operablyassociated with said spindle for restraining movement of said spindle ata determined end of said feed stroke to provide said axially restrainingpressure greater than and opposing said fluid means predeterminedpressure.
 11. A tool incorporating a positive feeding structure asdefined in claim 1 in which adjustment means is operably associated withcertain of said feed member, said fluid means and said feed actuatingmeans for selectively varying distance axially of said spindle betweensaid feed member first and second positions.
 12. A tool incorporating apositive feeding structure as defined in claim 1 in which said feedmember is telescoped over said spindle movable axially along saidspindle between said first and second positions; in which said fluidmeans includes an annular primary piston means telescoped over saidspindle and operably associated with said feed member for exerting saidpredetermined pressure axiaLly against said feed member, secondarypiston means operably connected to said primary piston means forsupplying liquid under pressure to said primary piston means; in whichsaid feed actuating means includes valve means operably associated withsaid secondary piston means of said valve means and said feed controlmeans, said valve means controlling air against said secondary pistonmeans of said fluid means and controlling air to said feed control meansfor shifting said feed control means, and control means operablyassociated with said valve means for controlling positioning of saidvalve means; and in which adjustment means is operably associated withsaid fluid means for selectively varying an internal volume of saidfluid means between said primary and secondary piston means toconsequently vary distance axially of said spindle between said feedmember first and second positions.